The Grote Kerk was built between 1470–1498 by Anthonius Keldermans. It is dedicated to St Lawrence contains the tomb of Floris V, Count of Holland (d. 1296), a brass of 1546, and some paintings (1507). The mechanical clock has 27 bells by Melchior de Haze (1600s), and 8 modern bells. The tower bell was made by Jan Moer in 1525, with a diameter or 130 cm.
The two organs are world-famous. The smaller one, called the 'Koororgel', was built in 1511 by Jan van Covelens, and is built against the North wall of the church. It is the oldest playable organ in the Netherlands. The larger organ at the west end of the church is one of the most famous, significant and beautiful organs in the world. It was built by Jacobus Caltus van Hagerbeer, finished in 1645. The magnificent casework, which unusually stretches from floor to vault and makes the organ part of the architecture of the church, was designed by Jacob van Campen, a leading architect of the time. The enormous canvas shutters were painted by Caesar van Everdingen.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.